The major emphasis of this project is to apply and advance mass spectrometric methods for the analysis of bacterial glycoconjugates. Our major scientific goal is to obtain an understanding of the structures and functions of the surface glycolipids or lipooligosaccharides (LOS) from pathogenic Neisseria and Haemophilusspecies. These studies include Haemophilus influenzae, Haemophilus ducreyi, Neisseria meningitidis and Neisseria gonorrhoeae. Hemophilus influenzae is responsible for a variety of serious adult and infant diseases e.g., meningitis, pheumonia. Haemophilus ducreyi causes the sexually transmitted disease, chancroid, which has also been identified as a significant independent risk factor in the transmission of AIDS. LOS components from these organisms contain some of the major epitopes or antigenic determinants, and we have shown that many of them are similar to glycolipid structures present in human tissue. One of our current hypothesis is that the similarity to human glycoconjugates is a form of host mimicry, perhaps providing a means for the bacteria to evade the host defenses, or to adhere and/or invade various human cell types. In H. ducreyi, we have shown the most strains contain LOS that are sialylated, and differences in sialylation have been correlated to its cytotoxicity and ability to adhere to human skin cells. An understanding of the structures and immunochemistry of LOS from these pathogenic bacteria could provide the means to develop a carbohydrate-based vaccine and/or drugs that could interfere with key evasion or adhesion processes. In addition, we will plan to investigate the structure of an important adhesion molecule, presumably belonging to the glycosylaminoglycan glyconjugate structure class, in pathogenic Chlamydia trachomatis. Therefore, we propose to develop more sensitive mass spectrometric-based strategies for the structural characterization of these bacterial glycoconjugates. Our ultimate aim is to develop massspectrometric techniques that will have the sensitivity to analyze samples directly from clinical samples (picomole to femtomole amounts) without in vitro growth, which is known to alter the distribution and abundances of the outermembrane lipooligosaccharides. We propose to use both electrospray and matrix-assisted laser desorption ionization methods to achieve this latter goal.